Sleep plays an important role in a person's overall health and enjoyment of life. The quality and quantity of sleep we receive each night affects our body's ability to function normally and the ability to reach peak performance. Physiologically, sleep affects our brain activity, heart rate, blood pressure, sympathetic nerve activity, muscle tone, blood flow to the brain, sexual arousal, and body temperature. Sleep deprivation shows a strong correlation to obesity, diabetes, stroke, depression, and hypertension. Restful sleep is dependent upon a persons comfort level while lying prone. The buildup or concentration of pressure on certain parts of the body and poor body alignment are significant causes of restless sleep. Sleeping on a mattress or other support surface that does not properly support and conform to the shape of your body or to the spine's natural curves may significantly contribute to restlessness or inability to sleep. The concept of having a 7-zone mattress or pad was derived from the fact that our bodies have different contours in different places and also different weights. The mattress or pad is fit for each of the seven major areas of the body—head and neck, shoulder and upper back, lumbar, pelvic, knee, lower leg, and foot and ankle. For example, the upper back and pelvis areas are softer, removing pressure points and ensuring better alignment of the spine and the lumbar area is firmer offering more support to the lower back. By reducing the buildup or concentration of pressure on certain points of the body, the 7-zone concept can alleviate restlessness or inability to sleep.